Filter assembly and airway pressure support system employing same

ABSTRACT

An airway pressure support system ( 2 ) includes a housing ( 4 ) having an air inlet opening ( 54 ), and a filter assembly ( 50 ) coupled to a plurality of receiving portions of the housing. The filter assembly is in fluid communication with the air inlet opening. The filter assembly includes a housing portion ( 62 ), a first filter media portion ( 64 ) attached to the housing portion, and first and second spring members ( 84, 86 ) attached to the housing portion, wherein the first and second spring members each have a floating portion and engage the plurality of receiving portions and cause a sealing force to be exerted against the filter assembly.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is the U.S. National Phase application under 35 U.S.C.§ 371 of International Application Serial No. PCT/EP2016/056766, filedon 29 Mar. 2016, which claims the benefit of U.S. Application Ser. No.62/140,488, filed on 31 Mar. 2015 and European Application No.15166118.8, filed on 1 May 2015. These applications are herebyincorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to airway pressure support systems, and,more particularly, to a filter assembly for use with an airway pressuresupport system, and an airway pressure support system employing such afilter assembly.

BACKGROUND OF THE INVENTION

EP1537903 discloses a respirator comprises a housing enclosing a fan orair pump, protected by a coarse filter, and a fine (breathing airquality) filter. The support frame of the fine filter forms an integralcomponent of the locating frame for the coarse filter, so that itsabsence prevents installation of the coarse screen, and renders thehousing visibly incomplete.

DE102010047565 discloses a respiration device has an air intake aperturefor intake of ambient air. A hygiene automatic backwashable cartridge(ABC) filter is positioned in the region of air intake aperture forfiltering the virus and bacteria in air flow to 99%.

Many individuals suffer from disordered breathing during sleep. Sleepapnea is a common example of such sleep disordered breathing suffered bymillions of people throughout the world. One type of sleep apnea isobstructive sleep apnea (OSA), which is a condition in which sleep isrepeatedly interrupted by an inability to breathe due to an obstructionof the airway; typically the upper airway or pharyngeal area.Obstruction of the airway is generally believed to be due, at least inpart, to a general relaxation of the muscles which stabilize the upperairway segment, thereby allowing the tissues to collapse the airway.Another type of sleep apnea syndrome is a central apnea, which is acessation of respiration due to the absence of respiratory signals fromthe brain's respiratory center. An apnea condition, whether OSA,central, or mixed, which is a combination of OSA and central, is definedas the complete or near cessation of breathing, for example a 90% orgreater reduction in peak respiratory air-flow.

Those afflicted with sleep apnea experience sleep fragmentation andcomplete or nearly complete cessation of ventilation intermittentlyduring sleep with potentially severe degrees of oxyhemoglobindesaturation. These symptoms may be translated clinically into extremedaytime sleepiness, cardiac arrhythmias, pulmonary-artery hypertension,congestive heart failure and/or cognitive dysfunction. Otherconsequences of sleep apnea include right ventricular dysfunction,carbon dioxide retention during wakefulness, as well as during sleep,and continuous reduced arterial oxygen tension. Sleep apnea sufferersmay be at risk for excessive mortality from these factors as well as byan elevated risk for accidents while driving and/or operatingpotentially dangerous equipment.

Even if a patient does not suffer from a complete or nearly completeobstruction of the airway, it is also known that adverse effects, suchas arousals from sleep, can occur where there is only a partialobstruction of the airway. Partial obstruction of the airway typicallyresults in shallow breathing referred to as a hypopnea. A hypopnea istypically defined as a 50% or greater reduction in the peak respiratoryair-flow. Other types of sleep disordered breathing include, withoutlimitation, upper airway resistance syndrome (UARS) and vibration of theairway, such as vibration of the pharyngeal wall, commonly referred toas snoring. Thus, in diagnosing a patient with a breathing disorder,such as OSA, central apneas, or UARS, it is important to detectaccurately the occurrence of apneas and hypopneas of the patient.

It is well known to treat sleep disordered breathing by applying apositive airway pressure (PAP) to the patient's airway using an airwaypressure support system that typically includes a mask, a pressuregenerating device, and a conduit to deliver positive pressure breathinggas from the pressure generating device to the patient through the mask.This positive pressure effectively “splints” the airway, therebymaintaining an open passage to the lungs. In one type of PAP therapy,known as continuous positive airway pressure (CPAP), the pressure of gasdelivered to the patient is constant throughout the patient's breathingcycle. It is also known to provide a positive pressure therapy in whichthe pressure of gas delivered to the patient varies with the patient'sbreathing cycle, or varies with the patient's effort, to increase thecomfort to the patient. This pressure support technique is referred toas bi-level pressure support, in which the inspiratory positive airwaypressure (IPAP) delivered to the patient is higher than the expiratorypositive airway pressure (EPAP).

Air filters, specifically air inlet filters, are an important part ofairway pressure support systems. Not only do they protect the innerworkings of the device by preventing foreign matter from entering theunit, but they also protect the patient from airborne contaminants. Inthe current airway pressure support system market, air filters aretypically die cut pieces of filter media that sit at the air inlet ofthe device.

There are two types of air filters that are commonly used in airwaypressure support systems. The first type of filter, referred to as acoarse particle filter, is structured to trap and filter relativelylarge pieces of gross particulate matter from the air before it entersthe airway pressure support system. The second type of filter, referredto as a fine particle filter, is designed to be employed in combinationwith a coarse particle filter and is structured to trap and filtersmaller pieces of particulate matter and airborne contaminants thatwould not otherwise be filtered by the coarse particle filter. Use of afine particle filter in an airway pressure support system is typicallyoptional. Thus, in practice, an airway pressure support system may beused with a coarse particle filter alone or with a combination of acoarse particle filter and a fine particle filter. When used incombination, the coarse particle filter and fine particle filter areplaced in series with one another. To ensure adequate filtration, thesefilters should create an airtight seal between each other and with thedevice itself. However, in current practice, the coarse particle filterand fine particle filter media are simply placed on top of each otherwithout any mechanism for applying a force to provide a secure seal.

In addition, coarse particle filters and fine particle filters aredesigned to be replaced and reimbursed by most insurance companies atdifferent time intervals. Most commonly, the coarse particle filter isreplaced every six months and the fine particle filter is replaced everythirty days.

SUMMARY OF THE INVENTION

There is thus a need for a filter assembly for devices such as airwaypressure support devices that is able to apply a sealing force in orderto ensure a secure seal as described above and that is able to hold botha coarse filter media and a fine filter media in a manner in which thefine filter media may be readily and easily replaced numerous times overthe life of the coarse filter media. The invention is defined by theindependent claims. The dependent claims define advantageousembodiments.

In one embodiment, an airway pressure support system, is provided thatincludes a housing having an air inlet opening, a gas flow generatorprovided within the housing, the gas flow generator being in fluidcommunication with the air inlet opening and being adapted to produce aflow of gas for delivery to a patient circuit operatively coupled to thegas flow generator, and a filter assembly coupled to a plurality ofreceiving portions of the housing. The filter assembly is in fluidcommunication with the air inlet opening. The filter assembly includes ahousing portion, a first filter media portion attached to the housingportion, and a plurality of spring members attached to the housingportion, wherein the plurality of spring members engage the plurality ofreceiving portions and cause a sealing force to be exerted against thefilter assembly.

In another embodiment, a filter apparatus structured to be coupled to ahousing of a device that employs a gas provided to the device throughthe filter apparatus is provided. The filter apparatus includes ahousing portion having a first opening and a second opening in fluidcommunication with the first opening, a first filter media portionattached to the housing portion such that the first filter media portioncovers the second opening and such that the housing portion and thefirst filter media portion define a chamber; and a plurality of springmembers attached to the housing portion, wherein the housing portion andthe plurality of spring members are a unitary component, and wherein theplurality of spring members are structured to engage a plurality ofreceiving portions of the housing of the device to cause a sealing forceto be exerted against the filter apparatus.

In yet another embodiment, a filter member is provided that includes aframe portion including an inner frame portion forming an opening, theinner frame portion including a plurality of inner walls positionedaround the opening, and an outer frame portion including a plurality ofouter walls. A first one of the inner walls and a first one of the outerwalls forms a first groove and a second one of the inner walls and asecond one of the outer walls forms a second groove, wherein the firstgroove is structured to receive a first portion of a housing portion ofa second filter member and the second groove is structured to receive asecond portion of the housing portion of the second filter member. Theinner frame portion is structured to be received within the housingportion of the second filter member to releasably secure the filtermember to the second filter member. The filter member also includes afilter media portion attached to the frame portion and covering theopening.

These and other objects, features, and characteristics of the presentinvention, as well as the methods of operation and functions of therelated elements of structure and the combination of parts and economiesof manufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to theaccompanying drawings, all of which form a part of this specification,wherein like reference numerals designate corresponding parts in thevarious figures. It is to be expressly understood, however, that thedrawings are for the purpose of illustration and description only andare not intended as a definition of the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an airway pressure support systemaccording to one particular, non-limiting embodiment in which thepresent invention in its various embodiments may be implemented;

FIGS. 2, 3, 4 and 11 are isometric views of a housing of the airwaypressure support system of FIG. 1 according to one particular,non-limiting exemplary embodiment;

FIGS. 5, 6, 7 and 8 are isometric, side elevational, front elevational,and bottom plan views, respectively, of a filter assembly of the airwaypressure support system of FIG. 1 according to one particular,non-limiting exemplary embodiment;

FIG. 9 is an exploded view of the filter assembly of FIGS. 5-8;

FIG. 10 is a cross-sectional view of the filter assembly of FIGS. 5-8taken along lines A-A FIG. 5;

FIGS. 12, 13, 14 and 15 are top plan, bottom plan, side elevational andfront elevational views, respectively, of a coarse particle filtermember of the filter assembly of FIGS. 5-8 according to the exemplaryembodiment; and

FIGS. 16, 17 and 18 are isometric, top plan, and bottom plan views,respectively, of fine particle filter member of the filter assembly ofFIGS. 5-8 according to the exemplary embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

As used herein, the singular form of “a”, “an”, and “the” include pluralreferences unless the context clearly dictates otherwise. As usedherein, the statement that two or more parts or components are “coupled”shall mean that the parts are joined or operate together either directlyor indirectly, i.e., through one or more intermediate parts orcomponents, so long as a link occurs.

As used herein, the word “unitary” means a component is created as asingle piece or unit. That is, a component that includes pieces that arecreated separately and then coupled together as a unit is not a“unitary” component or body. As employed herein, the statement that twoor more parts or components “engage” one another shall mean that theparts exert a force against one another either directly or through oneor more intermediate parts or components. As employed herein, the term“number” shall mean one or an integer greater than one (i.e., aplurality).

Directional phrases used herein, such as, for example and withoutlimitation, top, bottom, left, right, upper, lower, front, back, andderivatives thereof, relate to the orientation of the elements shown inthe drawings and are not limiting upon the claims unless expresslyrecited therein.

FIG. 1 is a schematic diagram of an airway pressure support system 2according to one particular, non-limiting exemplary embodiment in whichthe present invention may be implemented. Referring to FIG. 1, airwaypressure support system 2 includes a housing 4 which houses a gas flowgenerator 6, such as a blower used in a conventional CPAP or bi-levelpressure support device. Gas flow generator 6 receives breathing gas,generally indicated by arrow C, from the ambient atmosphere through afiltered air inlet 8 (described in greater detail herein) provided aspart of housing 4, and generates a flow of breathing gas therefrom fordelivery to an airway of a patient 10 at relatively higher and lowerpressures, i.e., generally equal to or above ambient atmosphericpressure. In the exemplary embodiment, gas flow generator 6 is capableof providing a flow of breathing gas ranging in pressure from 3-30cmH₂O. The pressurized flow of breathing gas from gas flow generator 6,generally indicated by arrow D, is delivered via a delivery conduit 12to a breathing mask or patient interface 14 of any known construction,which is typically worn by or otherwise attached to patient 10 tocommunicate the flow of breathing gas to the airway of patient 10.Delivery conduit 12 and patient interface device 14 are typicallycollectively referred to as a patient circuit.

Pressure support system 2 shown in FIG. 1 is what is known as asingle-limb system, meaning that the patient circuit includes onlydelivery conduit 12 connecting patient 10 to pressure support system 2.As such, an exhaust vent 16 is provided in delivery conduit 12 forventing exhaled gases from the system as indicated by arrow E. It shouldbe noted that exhaust vent 16 can be provided at other locations inaddition to or instead of in delivery conduit 12, such as in patientinterface device 14. It should also be understood that exhaust vent 16can have a wide variety of configurations depending on the desiredmanner in which gas is to be vented from pressure support system 2.

The present invention also contemplates that pressure support system 2can be a two-limb system, having a delivery conduit and an exhaustconduit connected to patient 10. In a two-limb system (also referred toas a dual-limb system), the exhaust conduit carries exhaust gas frompatient 10 and includes an exhaust valve at the end distal from patient10. The exhaust valve in such an embodiment is typically activelycontrolled to maintain a desired level or pressure in the system, whichis commonly known as positive end expiratory pressure (PEEP).

Furthermore, in the illustrated exemplary embodiment shown in FIG. 1,patient interface 14 is a nasal/oral mask. It is to be understood,however, that patient interface 14 can include a nasal mask, nasalpillows, a tracheal tube, an endotracheal tube, or any other device thatprovides a suitable gas flow communicating function. Also, for purposesof the present invention, the phrase “patient interface” can includedelivery conduit 12 and any other structures that couple the source ofpressurized breathing gas to patient 10.

In the illustrated embodiment, pressure support system 2 includes apressure controller in the form of a valve 18 provided in internaldelivery conduit 20 provided in housing 4 of pressure support system 2.Valve 18 controls the pressure of the flow of breathing gas from gasflow generator 6 that is delivered to patient 10. For present purposes,gas flow generator 6 and valve 18 are collectively referred to as apressure generating system because they act in concert to control thepressure and/or flow of gas delivered to patient 10. However, it shouldbe apparent that other techniques for controlling the pressure of thegas delivered to patient 10, such as varying the blower speed of gasflow generator 6, either alone or in combination with a pressure controlvalve, are contemplated by the present invention. Thus, valve 18 isoptional depending on the technique used to control the pressure of theflow of breathing gas delivered to patient 10. If valve 18 iseliminated, the pressure generating system corresponds to gas flowgenerator 6 alone, and the pressure of gas in the patient circuit iscontrolled, for example, by controlling the motor speed of gas flowgenerator 6.

Pressure support system 2 further includes a flow sensor 22 thatmeasures the flow of the breathing gas within delivery conduit 20 anddelivery conduit 12. In the particular embodiment shown in FIG. 1, flowsensor 22 is interposed in line with delivery conduits 20 and 12, mostpreferably downstream of valve 18. Flow sensor 22 generates a flowsignal, Q_(MEASURED), which is provided to a controller 24 and is usedby controller 24 to determine the flow of gas at patient 10(Q_(PATIENT)).

Techniques for calculating Q_(PATIENT) based on Q_(MEASURED) are wellknown, and take into consideration the pressure drop of the patientcircuit, known leaks from the system, i.e., the intentional exhaustingof gas from the circuit as indicated by arrow E in FIG. 1, and unknownleaks from the system, such as leaks at the mask/patient interface. Thepresent invention contemplates using any known or hereafter developedtechnique for calculating leak flow Q_(LEAK), and using thisdetermination in calculating Q_(PATIENT) based on Q_(MEASURED). Examplesof such techniques are taught by U.S. Pat. Nos. 5,148,802; 5,313,937;5,433,193; 5,632,269; 5,803,065; 6,029,664; 6,539,940; 6,626,175; and7,011,091, the contents of each of which are incorporated by referenceinto the present invention.

Of course, other techniques for measuring the respiratory flow ofpatient 10 are contemplated by the present invention, such as, withoutlimitation, measuring the flow directly at patient 10 or at otherlocations along delivery conduit 12, measuring patient flow based on theoperation of gas flow generator 6, and measuring patient flow using aflow sensor upstream of valve 18.

Controller 24 includes a processing portion which may be, for example, amicroprocessor, a microcontroller or some other suitable processingdevice, and a memory portion that may be internal to the processingportion or operatively coupled to the processing portion and thatprovides a storage medium for data and software executable by theprocessing portion for controlling the operation of airway pressuresupport system 2, including automatically controlling humidity asdescribed in greater detail herein.

An input/output device 26 is provided for setting various parametersused by airway pressure support system 2, as well as for displaying andoutputting information and data to a user, such as a clinician orcaregiver.

In the illustrated, non-limiting exemplary embodiment of the presentinvention, airway pressure support system 2 essentially functions as aCPAP pressure support system, and, therefore, includes all of thecapabilities necessary in such systems in order to provide appropriateCPAP pressure levels to patient 10. This includes receiving thenecessary parameters, via input commands, signals, instructions or otherinformation, for providing appropriate CPAP pressure, such as maximumand minimum CPAP pressure settings. It should be understood that this ismeant to be exemplary only, and that other pressure supportmethodologies, including, but not limited to, BiPAP AutoSV, AVAPS, AutoCPAP, and BiPAP Auto, are within the scope of the present invention.

FIGS. 2, 3 and 4 are isometric views of housing 4 of airway pressuresupport system 2 according to one particular, non-limiting exemplaryembodiment. FIG. 2 shows housing 4 in a fully assembled condition andFIGS. 3 and 4 show housing 4 in partially disassembled conditionsdescribed below. Housing 4 is constructed from multiple components and,when assembled, includes a top wall 28, a bottom wall 30, a front wall32, a rear wall 34, a first side wall 36 and a second side wall 38. Asseen in FIGS. 2-4, front wall 32 includes input/output device 26 in theform of a display screen 40 and an input dial 42. In addition, as alsoseen in FIGS. 2-4, second side wall 38 includes an access door 44 whichcovers and provides selective access to a data port 46 which receives astorage device 48 (e.g., an SD card) for storing therapy related datagenerated during use of airway pressure support system 2. Access door 44also provides selective access to filtered air inlet 8. In the exemplaryembodiment, filtered air inlet 8 comprises a port structure 52 (shown inFIGS. 3 and 4) and a two piece filter assembly 50 that is structured tobe selectively coupled to and received within the port structure 52.

FIG. 2 shows filter assembly 50 in an assembled condition and receivedwithin port structure 52, FIG. 3 shows filter assembly 50 in anassembled condition but removed from port structure 52, and FIG. 4 showsfilter assembly 50 is a disassembled condition and removed from portstructure 52. As seen in FIGS. 3 and 4, port structure 52 includes anopening 54 which provides fluid access to the input of blower 6 toenable air, filtered by filter assembly 50, to be drawn into gas flowgenerator 6. Port structure 52 also includes a first slot member 56A anda second slot member 56B positioned adjacent to opposite sides ofopening 54. First slot member 56A and second slot member 56B eachgenerally have a “square C” shape including first and second side wallportions on opposite sides of a central wall portion. The significanceof this feature is described elsewhere herein.

FIGS. 5, 6, 7 and 8 are isometric, side elevational, front elevational,and bottom plan views, respectively, of filter assembly 50 in anassembled condition. FIG. 9 is an exploded view of filter assembly 50,and FIG. 10 is a cross-sectional view of filter assembly 50 taken alonglines A-A in FIG. 5. As seen in FIGS. 5-10, filter assembly 50 includesa coarse particle filter member 58 that is structured to be selectivelyand releasably attached to a fine particle filter member 60 in a mannerwherein a generally airtight seal is provided between the two members.As described in detail elsewhere herein, in one aspect, filter assembly50 is structured to be coupled to housing 4 at port structure 52 toprovide both coarse particle and fine particle filtering in a manner inwhich a sealing force is automatically applied to coarse particle filter58 and fine particle filter 60. Such a force ensures that a secure sealis provided between those two components and between filter assembly 50and housing 4. In addition, as also described herein, coarse particlefilter member 58 is structured to be able to hold multiple similarlystructured fine particle filter members 60 over the life of coarseparticle filter member 50 due to the releasable connection between thetwo members. Furthermore, as described in detail herein, in anotheraspect shown in FIG. 11, coarse particle filter member 58 is alsostructured to be coupled to housing port 4 at port structure 52 withoutfine particle filter member 60 in a manner wherein a sealing force isautomatically applied to coarse particle filter member 58 to ensure thata secure seal is provided directly between coarse particle filter member58 and housing 4.

FIGS. 12, 13, 14 and 15 are top plan, bottom plan, side elevational andfront elevational views, respectively, of coarse particle filter member58 according to the exemplary embodiment. Coarse particle filter member58 includes a housing portion 62 and a coarse particle filter mediaportion 64 attached to housing portion 62 within a first openingprovided in housing portion 62. In the non-limiting, exemplaryembodiment, housing portion 62 is made of a resilient material such as,without limitation, an injection molded thermoplastic or silicone.Coarse particle filter media portion 64 is, in the non-limitingexemplary embodiment, a piece of woven or non-woven fabric (e.g.polyester) filter material that is attached to housing portion 62 by anysuitable means, such as, without limitation, ultrasonic welding. In theexemplary embodiment, coarse particle filter media portion 64 is asingle layer material that has a filtration capacity and pressure dropthat are each lower than the filtration capacity and pressure drop offine particle filter 60.

Housing portion 62 includes a main housing portion 66 and an opening 68providing access to a chamber defined by main housing portion 66. Aswill be appreciated, opening 68 is structured to permit the flow of gasthrough coarse particle filter member 58 and in particular throughcoarse particle filter media portion 64. In addition, main housingportion 66 includes a bottom perimeter portion 70 including edgeportions 72, 74, 76 and 78 which define a second opening spaced from thefirst opening described above. Also, main housing portion 66 includessidewalls 80 and 82 provided on opposite lateral sides of main housingportion 66. Finally, housing portion 62 of coarse particle filter member58 includes a first spring member 84 attached to side wall 80 and asecond spring member 86 attached to side wall 82.

In the illustrated, exemplary embodiment, first spring member 84 andsecond spring member 86 are each elongated arm members made out of thesame material as main housing portion 66 (e.g., molded with main housingportion 66) and each include a proximal end 88 attached to theassociated side wall 80, 82 and a free moving (i.e., floating) distalend 90. In addition, as seen in FIG. 14, the arm member of first springmember 84 and second spring member 86 includes a ramp portion 92directly connected to the distal end 88 and an arced portion 94 at theproximal end 90. The significance of these features is describedelsewhere herein.

Furthermore, it will be appreciated that the particular embodiments offirst spring member 84 and second spring member 86 described above arejust one exemplary embodiment, and that first spring member 84 andsecond spring member 86 may take on different structures within thescope of the present invention. For example, and without limitation,first spring member 84 and second spring member 86 may be separatespring components (e.g., metal coil springs) that are attached tosidewalls 80 and 82.

FIGS. 16, 17 and 18 are isometric, top plan, and bottom plan views,respectively, of fine particle filter member 60 according to theexemplary embodiment. Find particle filter member 60 includes a frameportion 96 and a coarse particle filter media portion 98 attached toframe portion 96. In the non-limiting, exemplary embodiment, frameportion 96 is made of an elastomeric material that is softer than thematerial of main housing portion 66 such as, without limitation, aninjection molded thermoplastic elastomer. In one exemplary embodiment,frame portion 96 is made of a material having a durometer of about 40-90Shore A (in one particular embodiment, frame portion 96 is made of amaterial having a durometer of about 70-80 Shore A). In contrast, mainhousing portion 66 is made of a much harder material, such as athermoplastic (e.g., polycarbonate), which may have a durometer ratingof 75-90 Rockwell M. Fine particle filter media portion 98 is, in thenon-limiting exemplary embodiment, a piece of woven or non-woven fabric(e.g. polyester) filter material that is attached to frame portion 96 byany suitable means, such as, without limitation, an overmolding process.In the exemplary embodiment, fine particle filter media portion 98 is anon-woven synthetic material having multiple layers for greaterfiltration and may be made of a blended synthetic fiber and spunbondpolypropylene.

Frame portion 96 includes an inner frame portion 100 forming an apertureover which fine particle filter media portion 98 is positioned. Innerframe portion 100 includes walls 102, 104, 106, and 108. Walls 102 and106 include protruding members 110 extending therefrom, the function ofwhich is described elsewhere herein. In addition, frame portion 96includes an outer frame portion including outer walls 114 and 116. Asseen in FIGS. 16 and 17, wall 102 and outer wall 114 form a first groove118 and wall 106 and outer wall 116 form a second groove 120. Inaddition, outer wall 114 and outer wall 116 each include a number ofprotruding members 122. The function of these elements is describedbelow.

Referring to FIG. 9, filter assembly 50 is assembled by inserting edgeportions 72 and 76 of coarse particle filter member 58 into grooves 118and 120 of fine particle filter member 60. When this is done, innerframe portion 100 will be received within the perimeter created by theinside of edge portion 72, 74, 76 and 78 in a manner such that thoseedge portions will engage inner frame portion 100. Furthermore,protruding members 110 and 122 extend onto grooves 118 and 120 andprovide an interference/friction fit to hold coarse particle filtermember 58 and fine particle filter member 60 together until separatedfrom one another by a user with some degree of force.

After filter assembly 50 is assembled as just described, it may beinserted into port structure 52. In particular, filter assembly 50 isinserted into port structure 52 rear side (i.e. the side oppositeopening 68) first in a manner wherein first spring member 84 is receivedwithin the first slot member 56A of port member 52 and second springmember 86 is received within second slot member 56B of port member 52.When this is done (see FIG. 2), the top side wall of each slot member56A, 56B will engage (e.g., directly contact in the illustrated example)the respective distal end 94 of each spring member 84, 86. As a resultof such engagement, a downward force will be exerted against both coarseparticle filter member 58 and fine particle filter member 60 that willresult in a seal being created between those two members and betweenfine particle filter member 60 and housing 4.

In addition, coarse particle filter member 58 alone (i.e., with fineparticle filter member 60 separated therefrom) may also be in insertedinto port structure 52 in a like manner when it is desired to provideonly coarse filtering capabilities. When this is done, due to theflexible nature of first spring member 84 and second spring member 86,those members will be able to flex and still engage (e.g., directlycontact in the illustrated example) the top side wall of each slotmember 56A, 56B such that sealing force is exerted and a suitable sealis created between coarse particle filter member 58 and housing 4. Thiscondition is illustrated in FIG. 11.

Thus, the integral spring feature(s) of coarse particle filter member 58allows it to float and apply a force against the inlet of housing 4. Asdescribed above, this float will allow the placement of fine particlefilter member 60 in series with coarse particle filter member 58 whilestill maintaining a force to ensure an airtight seal. In other words,coarse particle filter member 58 will self-adjust depending upon whetherit is used by itself or with fine particle filter member 60. As alsodescribed above, coarse particle filter member 58 and fine particlefilter member 60 are structured and shaped to allow coarse particlefilter member 58 to be nested within fine particle filter member 60.This will create good alignment for filtration and allow ease of use forthe end user.

Accordingly, as described herein, the disclosed concept provides afilter assembly for devices such as airway pressure support devices thatis able to apply appropriate sealing forces the filter assembly and thatis also able to hold both a coarse filter media and a fine filter mediain a manner that allows the fine filter media to be readily and easilyreplaced numerous times over the life of the coarse filter media.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. The word “comprising” or “including”does not exclude the presence of elements or steps other than thoselisted in a claim. In a device claim enumerating several means, severalof these means may be embodied by one and the same item of hardware. Inany device claim enumerating several means, several of these means maybe embodied by one and the same item of hardware. The mere fact thatcertain elements are recited in mutually different dependent claims doesnot indicate that these elements cannot be used in combination.

Although the invention has been described in detail for the purpose ofillustration based on what is currently considered to be the mostpractical and preferred embodiments, it is to be understood that suchdetail is solely for that purpose and that the invention is not limitedto the disclosed embodiments, but, on the contrary, is intended to covermodifications and equivalent arrangements that are within the scope ofthe appended claims. For example, it is to be understood that thepresent invention contemplates that, to the extent possible, one or morefeatures of any embodiment can be combined with one or more features ofany other embodiment.

The invention claimed is:
 1. An airway pressure support system,comprising: a housing having a port structure with an air inlet opening,the air inlet opening being disposed on a horizontal surface of the portstructure, the port structure further including a first slot member anda second slot member within a respective first vertical side and secondvertical side of the port structure; and a filter assembly coupled tothe housing via the port structure, the filter assembly being in fluidcommunication with the air inlet opening, wherein the filter assemblyincludes a housing portion having a first vertically disposed side wall,a second vertically disposed side wall opposite the first side wall, afront vertically disposed wall provided between the first side wall andthe second side wall, a top wall connected to the front wall, the firstside wall and the second side wall, and a bottom horizontally disposedportion opposite the top wall and having a first opening formed therein,the filter assembly further including a first filter media portionattached to the bottom portion, wherein the first filter media portioncovers the first opening, and wherein the first filter media portion,the first side wall, the second side wall, the front wall, the top walland the bottom portion form an inner chamber having a second openingopposite the front wall and in fluid communication with the firstopening, via the first filter media portion, the filter assembly stillfurther including a first spring member provided on an exterior of thefirst side wall, and a second spring member provided on an exterior ofthe second side wall, wherein the first and second spring members eachhave a vertically disposed floating portion configured to engage arespective top wall of the first slot member and the second slot memberand provide a downward sealing force to be exerted against the filterassembly to create a seal between the bottom portion of the filterassembly and air inlet opening of the port structure of the housing, inresponse to the filter assembly being inserted into the port structure.2. The airway pressure support system according to claim 1, wherein thefilter assembly comprises a coarse particle filter member coupled to afine particle filter member.
 3. The airway pressure support systemaccording to claim 2, wherein the housing portion, the first filtermedia portion, and the first and second spring members are part of thecoarse particle filter member, wherein the fine particle filter memberincludes a second filter media portion positioned in series with thefirst filter media portion, wherein the second filter media portion isstructured to filter a smaller particle size than the first filter mediaportion, and wherein the first and second spring members engage therespective top wall of the first slot member and the second slot memberand cause the sealing force to be exerted against the coarse particlefilter member and the fine particle filter member.
 4. The airwaypressure support system according to claim 2, wherein the fine particlefilter member is releasably coupled to the coarse particle filtermember.
 5. The airway pressure support system according to claim 4,wherein the fine particle filter member includes a frame member, whereinthe second filter media portion is attached to the frame member, whereinthe housing portion of the filter assembly includes a number of firstfeatures structured to be mated with a number of second features of theframe member to enable the fine particle filter member to be releasablycoupled to the coarse particle filter member.
 6. The airway pressuresupport system according to claim 5, wherein the number of firstfeatures includes a number of edge portions provided on the housingportion of the filter assembly and wherein the number of second featuresincludes a number of grooves provided in the frame member of the fineparticle filter.
 7. The airway pressure support system according toclaim 1, wherein the first spring member comprises a first arm memberhaving a first proximal end connected to the first side wall, whereinthe second spring member comprises a second arm member having a secondproximal end connected to the second side wall.
 8. The airway pressuresupport system according to claim 7, wherein the floating portion of thefirst spring member is a floating first distal end of the first armmember, the floating portion of second spring member is a floatingsecond distal end of the second arm member, and wherein the floatingfirst distal end engages a first top wall of the first slot member ofthe port structure of the housing, and the floating second distal endengages a second top wall of the second slot member of the portstructure of the housing.
 9. The airway pressure support systemaccording to claim 7, wherein the housing portion, the first springmember and the second spring member of the filter assembly are a unitarycomponent.
 10. The airway pressure support system according to claim 7,wherein the first arm member includes a first ramp portion directlyconnected to the first proximal end and a first arced portion at adistal end of the first arm member, and wherein the second arm memberincludes a second ramp portion directly connected to the second proximalend and a second arced portion at a distal end of the second arm member.11. A filter apparatus structured to be coupled to a housing of a devicethat employs a gas provided to the device through the filter apparatus,the filter apparatus comprising: a housing portion having a firstvertically disposed side wall, a second vertically disposed side wallopposite the first side wall, a front vertically disposed wall providedbetween the first side wall and the second side wall, a top wallconnected to the front wall, the first side wall and the second sidewall, and a bottom horizontally disposed portion opposite the top walland having a first opening formed therein; a first filter media portionattached to the bottom portion; wherein the first filter media portioncovers the first opening, and wherein the first filter media portion,the first side wall, the second side wall, the front wall, the top walland the bottom portion form an inner chamber having a second openingopposite the front wall and in fluid communication with the firstopening, via the first filter media portion; and a first spring memberprovided on an exterior of the first side wall, and a second springmember provided on an exterior of the second side wall, wherein thefirst and second spring members each have a vertically disposed floatingportion configured to engage a respective top wall of a first slotmember and a second slot member of a port structure of the housing ofthe device and provide a downward sealing force to be exerted againstthe filter apparatus to create a seal between the bottom portion and anair inlet opening of a port structure of the housing of the device, inresponse to the filter apparatus being inserted into the port structure.12. A filter assembly including the filter apparatus according to claim11, wherein the filter apparatus comprises a coarse particle filtermember, wherein the filter assembly further comprises a fine particlefilter member releasably coupled to the coarse particle filter member,wherein the fine particle filter member includes a second filter mediaportion positioned in series with the first filter media portion,wherein the second filter media portion is structured to filter asmaller particle size than the first filter media portion, and whereinthe first and second spring members are structured to engage therespective top wall of the first slot member and the second slot memberand cause the sealing force to be exerted against the coarse particlefilter member and the fine particle filter member.